Thermostatic switch



1934- B. E. GETCHELL THERMOSTATIC SWITCH Filed Dec. 9, 1933 INSULATIONETCHELL,

BENJAMI INVENTOR .E G

Patented Dec. 4, 1934 g g j 1,983,076

. THEBMOSTATIC swrron Getchell, Plalnville,

Com, assignor to The Trumbull Electric Manufacturing Comparry,Plainville, Conm, a corporation of Connecticut .Application December 9,1933, Serial No. 701,714

5 Claims.

My invention relates to'improvements in the invention of my formerPatent 1,928,484.

Constructions of this character under some conditions developdifliculties which it is my present object to overcome.

One object is to provide a construction which is more positive in itsaction.

Another object is to provide a construction which can be made verysensitive.

Another-object is to provide a construction which cannot be warped outof shape by subjection to abnormal temperature changes. a

Another object is to provide a simple form of construction which can bemade and assembled in such a way as to produce reliable and dependable.movements under predetermined temperature-conditions. I

In carrying out the invention I provide a warping thermostatic strip orarm with-a spring biased hinged switch member at'its end as in my formerpatent and enclose one end 01' the snapping spring by a cup-like washerwhich is supported by. a knife edge or equivalent arrangemen Thebi-metallic thermostatic strip. in this case is supported by one end of-a bar which projects from the insulating basemand this bar serves notonly as a support buts-as an abutment to limit the warping action of thearm. Additional stops are also preferably provided to. limit the actionof the arm away from the supporting bar. The arm, as in my formerpatent, is "provided with -means for adjusting or varying its action.

Fig. 1 is a plan view of one form of device embodying my invention withthe parts in the-closed circuit oron position.

' Fig..2.is a side view and partial section of the same.

Fig. 3 is a transverse section on the plane of the line 3-3 of Fig. 2.

.Fig. 4. is an enlarged fragmentary sectional view showing the contactmembers separated.

Fig. .5 is an exploded perspective view showing the movable end of, thethermostatic arm, the

abutment washer and the movableswitch-member.

The parts are preferably supported by base '7 which also carries circuitterminals 8 and 9 for the stationary and movable switch contactsrespectively. 'The stationary contact 10 is secured to the terminal 8and projects from the base at a substantially right angle. The movableswitch contact member 11 is hinged to the movable end of the bi-metallicthermostatic arm or strip 12 whose other end is secured to and supportedby I the abutment bar 13. This bar is secured to the base as, forinstance, by riveted portions 14 and 15. The arm is secured to the barin any suitable manner as, for instance, by a screw or rivet 16 and anadjustment screw 1'1 is provided for giving an initial set or directionto the warping arm 12. This bar 13 extends substantially the entirelength of the thermostatic arm so as to limit the warping movement ofthe arm in that direction. On the opposite side of the arm I preferablyprovide stops 18 and I9.

The hinged contact member 11 is connected to the thermostatic arm by ahook-like portion 20 which embraces the cross piece 21 so as to permitthe arm 11 to swing about this cross piece. The spring 22 surrounds apart of the contact finger between the shoulders 23 and the washer 24.This washer is provided with grooves 25 to receive the knife-like tip 26of the thermostatic arm.

The washer is preferably provided with a flange 27 which surrounds thelarger end of the spring 22 so as to preventrelative displacement. Thestationary abutment 28 is provided opposite the contact portion 10 sothat the switch member 11 is limited in its movement between the parts10 and 28. a

While I have shown the part 28 as of insula tion it is obvious that itmight be made conductive to constitute another circuit terminal.

As above pointed out while the construction of my former patent hasdesirable characteristics there 'are certain conditions under which sucha device may not function as intended. For instance, if we assume thatthe switch member 11 is moved into the position shown in Fig. 1 inresponse to a decrease in temperature, a fur-- ther or excessive drop intemperature may cause the thermostatic element 12 to continue to bow inan arcuate form in such a manner as to snap the switch member to theopen circuit position which is directly contrary to its intendedfunction. abutment bar 13 above the thermostatic arm such an excessivewarping action is prevented.

The present construction also more accurately relates the hinged switchmember 11 to the thermostatic arm by reason of the knife edge support ofthe washer 24 on the end of the arm and further by reason of the lateralflange of the washer which confines the large end of the spring.

It will also be seen that by the present construction I provide circuitterminals which are riveted directly to the supporting members for therespective switch contacts so that there is By providing the stationaryno likelihood of a poor electrical connection 1be-' ing'established bydefective screws or the like.

I claim: v

1. A thermostatic device including an insulatingbase, a supportingabutment bar carried by the base, a bi-metallic arm secured at one endto said bar and movable at the other end toward and from said bar,said'bar serving to limit the warping movement of said arm in onedirection, a stop limiting the movement of said arm away from said bar,a stationary contact and a spring pressed switch member hinged to themovable end of said am and adapted to engage said stationary contact. r

2. A thermostatic device including an insulating base, a supportingabutment bar carried by the base and extending edgewise thereupon, abi-metallic arm secured at one end to said bar and movable at the otherend towardand from said bar and parallel with said base, a stop limitingthe movement of said arm away from said bar, two stationary abutmentsand a spring pressed switch member end of said arm and adapted to snapbetween said abutments.

3. A thermostatic switch including a supporting base, a thermostatic armhaving one end supported by said base and having a knife edge at theopposite end, a switch member having a hinged connection with said armincluding a hinged to the movablev posed between the spring washerhaving a grooved portion for engagement with said knife edge and acupped portion, and a direction, stops near the opposite ends forlimiting the movement of said arm away from said bar, a stationarycontact and a spring pressed switch member hinged to the movable end ofsaid arm and adapted to engage said stationary contact.

5. A thermostatic switching device including a stationary contact, amovable contact, a bi-me-j tallic arm supported at one of its ends andhaving its opposite end free .to move for actuating said movablecontact, a compression spring actuated by said arm for imparting a snapaction to the contact movement and a cup-shaped washer for seating oneend of said spring and dis- I and arm to permit uniform action of thespring, said washer having a grooved portion forming a pivot seat forthe movable end portion of saidbi-metallic arm.

BENJAMIN E. GETCHEIL.

